Simultaneous degradation of high concentration of citric acid coupled with electricity generation in dual-chamber microbial fuel cell

Citric acid (CA) production wastewater has been attracting wide attention because of its potential threat to environment and public health. Microbial fuel cell (MFC) can satisfy the urgent demands of high efficiency, last sustainability and environmental-friendly wastewater treatment. In this work, the performance of MFC towards CA degradation and the corresponding power generation were both investigated. Four different contents of CA (5 mM, 10 mM, 25 mM, 40 mM) were selected for preparation of stimulated wastewater, and the maximum chemical oxygen demand (COD) removal and power density reached to 79.4% and 610 mW/m(2), respectively at the CA content of 25 mM. Besides, the decrease of influent pH from 7 to 4 can reduce the electrochemical properties of microorganisms, while negligible effect on electricity generation was observed with pH higher than 6. Besides, the addition of riboflavin as redox mediators enhanced power generation and COD removal rate simultaneously, which increased from 611 mW/m(2), 79.4% to 855.2 mW/m(2), 84.5% respectively. Significantly, anodic microorganisms can survive well in the presence of 40 mM citric acid and remain its electricity generation and degradation capability simultaneously by sequencing analysis. Therefore, it is anticipated that the MFC system seems to be a promising technology for organic wastewater treatment effectively and accessibly.